NEW YORK -- Gene Upshaw, the Hall of Fame guard who during a quarter century as union head helped get NFL players free agency and the riches that came with it, has died. He was 63.

Upshaw died Wednesday night at his home in Lake Tahoe, Calif., of pancreatic cancer, which was diagnosed only last Sunday, the NFL Players Association said Thursday. His wife, Terri, and sons Eugene Jr., Justin and Daniel were by his side.

Upshaw had not been feeling well for about a week and his wife had even noticed his breathing had become somewhat labored, sources told ESPN's Chris Mortensen. She convinced him to go to the emergency room on Sunday, and that's where he was diagnosed.

Upshaw's family is going to have only a private service. The league and NFL commissioner Roger Goodell are in discussions with players' association president Kevin Mawae, who plays center for the Titans, on how to honor Upshaw, but they have not yet come to a conclusion, Mortensen is reporting.

A Singular Career

Highlights of Gene Upshaw's numerous contributions to pro football for four-plus decades:

• Executive director of NFLPA since June 1983

• Took part in all negotiations leading up to CBA in 1977, '82 and '93 (and extensions in '96, '98, '02 and '06)

• Only player ever to start on championship teams in both the AFL and NFL

• NAIA All-America honors at Texas A&I

There will be a more public memorial service sometime in September, most likely in the Washington, D.C., area, where the players' association is headquartered.

NFLPA General Counsel Richard Berthelsen has been named acting executive director of the NFLPA, a source on the executive committee told ESPN.com's Bill Williamson.

"Few people in the history of the National Football League have played the game as well as Gene and then had another career in football with so much positive impact on the structure and competitiveness of the entire league as Gene," former NFL commissioner Paul Tagliabue said.

Goodell offered similar praise.

"Gene Upshaw did everything with great dignity, pride, and conviction," Goodell said.

"He was the rare individual who earned his place in the Pro Football Hall of Fame both for his accomplishments on the field and for his leadership of the players off the field. He fought hard for the players and always kept his focus on what was best for the game. His leadership played a crucial role in taking the NFL and its players to new heights."

His death was first reported by Clear Channel Online on several radio Web sites.

Upshaw's death came only two days after the union announced he would hold a briefing on labor negotiations before the Sept. 4 season opener between Washington and the New York Giants.

"It is a very, very sad day. He was a leader without peers and a dear friend who I will never forget," NFLPA outside counsel Jeffrey Kessler said.

Upshaw's outstanding 15-season playing career was entirely with the Oakland Raiders and included two Super Bowl wins and seven Pro Bowl appearances. His biography was posted on the front page of the Hall of Fame Web site Thursday along with his enshrinement speech from 1987.

In 1983, Upshaw became executive director of the players' association and guided it through the 1987 strike that led to replacement football. By 1989, the players had a limited form of freedom, called Plan B, and in 1993, free agency and a salary cap were instituted.

ESPN Radio

Appearing on Mike and Mike in The Morning, Mike Ditka offered his thoughts on Gene Upshaw the player, the man, and the head of the NFLPA. Listen

Since then, the players have prospered so much that NFL owners recently opted out of the latest labor contract, which was negotiated two years ago by Upshaw and then-commissioner Paul Tagliabue.

Upshaw was criticized by some for not being tough enough in talks with Tagliabue, a close friend of the union head. He also was blamed by many older veterans for not dealing sufficiently with their health concerns.

He never took criticism lightly and often said what he thought without weighing the consequences from a public relations standpoint. Once, when he came under fire for the problems of retired players from Joe DeLamielleure, also a Hall of Fame guard, Upshaw retorted: "I'd like to break his neck."

DeLamielleure was one of the first to respond to Upshaw's death.

"The reality of life for all the guys who played in the NFL, including Gene, is that we have a short life span. It's just the way it is," he said. "I have sympathy for his family. I have sympathy for his wife and children. I didn't know Gene personally. I just knew him professionally."

Despite the criticism, players prospered under Upshaw.

The salary cap for this season is $116 million and the players are making close to 60 percent of the 32 teams' total revenues, as specified in the 2006 agreement. In all, the players will be paid $4.5 billion this year, according to owners.

Upshaw recently became more aggressive in his dealings with the owners and Tagliabue's successor, Goodell. Owners opted out of the collective bargaining agreement, which means a season without a salary cap in 2010. Upshaw declared the cap would disappear for good should there be no new deal by March 2010.

Gene Upshaw

Kevin Terrell/WireImage.com

Gene Upshaw, a Pro Football Hall of Fame guard, was the lead voice for NFL players for the better part of the past two decades.

"I'm not going to sell the players on a cap again," Upshaw said. "Once we go through the cap, why should we agree to it again?"

That was one of the reasons the owners wanted him out. NFL officials and owners claimed players are getting a disproportionate amount of the revenue. Upshaw's supporters said management's viewpoint indicates he did his job well.

Still, the most influential owners respected him.

"Gene and I developed a close friendship that remained strong through the good times and some of the NFL's most difficult challenges," said Pittsburgh Steelers chairman Dan Rooney. "We worked very closely on key issues that allowed the NFL to maintain unprecedented labor peace. His biggest asset was his understanding of the business of the game, and you always knew that his concern for the game's best interests guided his actions."

Garber on Upshaw
From March 2006: ESPN.com senior writer Greg Garber profiled Gene Upshaw and his impressive set of accomplishments, from a Hall of Fame playing career to 23 years leading the NFLPA. Story

The players called a strike in 1987 -- leading to games with replacements -- and it wasn't until 1993 that labor peace was reached with a breakthrough seven-year contract which included free agency and a salary cap. Almost ever since, player salaries have spiraled up along with revenue from television and marketing deals made by the league.

The NFLPA also has its own marketing arm, Players Inc., established in 1994, that has grown into a multimillion dollar operation.

Upshaw faced controversy in 2006 when some 325 retired players from the AFL and NFL came forward with accounts of being given minimal disability benefits.

Baltimore Ravens kicker Matt Stover had been leading an effort to oust Upshaw as the NFLPA executive director. In April, he e-mailed a plan to fellow player representatives to have a new union boss in place by March 2009.

Upshaw responded, speaking of the looming labor confrontation with owners when the current contract expires, by saying: "I would never leave until this deal is done."

Frequently listed as one of the most powerful men in U.S. sports, Upshaw was drafted in the first round by Oakland in 1967 out of Texas A&I -- hardly a football factory. He was an NAIA All-American at center, tackle and end, but was switched to left guard by the Raiders.

And that's where he stayed through a magnificent career that included 10 conference championship games as well as the Super Bowl victories.

His playing career was summed up Thursday by his close friend and fellow Hall of Famer Art Shell, who played next to him on Oakland's offensive line and who, in 1989, became the first black coach of the modern era when he took over the Raiders.

"Gene was a true pioneer as one of the few African-American leaders of a major union," Shell said. "He was the equal of owners in negotiations and made the league a better place for all players. Playing alongside of Gene was an honor and a privilege. He was a pillar of strength and leadership for our great Raider teams."

Information from ESPN's Chris Mortensen, ESPN.com's Bill Williamson and The Associated Press was used in this report.